Although the bomb was discovered later during a manual search, the security dummy run highlights gaps which need to be improved if London is to feel protected from terrorist attacks during the Olympics.

The amount of explosives (equivalent to standard luggage allowance on planes) and the proximity to the event have caused concern.

Around 30 sniffer dogs work on the London Olympic site in Stratford. Police labradors, springer spaniels and cocker spaniels have embarked on special training courses with their handlers in order to ensure the dogs are adept at searching for explosives. But the highly skilled security role, which is challenging for both the handlers and animals, can become problematic if the intelligent dogs get bored.

A spokesman for the Metropolitan Police Service (MPS) said: "The MPS has provided support to the Olympic Delivery Authority's (ODA) assurance process that is being run at the Olympic Park.

"The ODA also runs its own security resilience tests to ensure that preparations for the London 2012 Games are as robust as possible."

An Olympic spokesman added: "We test rigorously and regularly, to ensure that we will deliver a safe and secure Games."

The budget required to provide security for the Olympics is continually rising. Although officially the figure is reportedly £600million, a further £238 million is available in case of a terrorist threat.

Assistant police commissioner Chris Allison, who is the National Olympic Security co-ordinator, told the London Assembly in November 2011: "Can I tell you how much money I need? No I cannot, I can't tell you what the final costs are going to be."